(a) Field of the invention
The present invention relates to a new semiconductor device which is capable of attaining the goal of size reduction and of extremely high operating speed which conventional semiconductor devices have not realized. More particularly it pertains to a semiconductor device comprising an electrode (which is called the source electrode) for injecting carriers and another electrode (which is called the drain electrode) for receiving these carriers. The potential distribution existing in the foreground of the source electrode is controlled by virtue of a static induction effect by the voltage applied to still another electrode, which is a controlling electrode, to thereby control the tunnel injection current from the source electrode.
(b) Description of the prior art
Conventional transistors which are operated based on the principle of controlling of carrier injection include, typically, bipolar transistors (hereinafter to be referred to as BPT) and static induction transistors (hereinafter to be referred to as SIT). In a BPT, the potential of the base region relative to the emitter region thereof is controlled, via a base resistance, by the voltage applied to the base electrode which serves as the controlling electrode, to thereby control the amount of minority carriers which flow into the base region from the emitter region. On the other hand, in an SIT, the channel region through which a current is allowed to flow is almost or completely depleted, and the potential which this channel region has is controlled, via the capacitance of said depletion layer, by the voltage applied to the gate electrode which is the controlling electrode, i.e. capacitive control, to thereby control the amount of carriers injected into the drain region from the source region. In each of these two types of conventional transistors, the flow of current is controlled by varying the amount of those carriers having such thermal energy as allowing them to pass over the potential barrier, by varying the height of this potential barrier. Therefore, in such conventional SITs, those carriers which pass over the potential barrier will gather at the foreground of the potential barrier. In such instance, the pattern of conduction mechanism of conventional BPT and SIT is inevitably accompanied by a carrier storage effect between the source region or emitter region and the potential barrier height. In contrast thereto, tunnel injection does not follow such pattern. Accordingly, in the conventional devices, there still exists some carrier storage effect, though not so large, between the region where a potential barrier is produced and the region where either the source region or emitter region is formed. This carrier storage effect has, in the past, constituted a cause of limitation to the speed in materializing ultra-high speed operation.